Chemical degradation of thermoplastic polyurethane for recycling polyether polyol

Thermoplastic polyurethane, based on 4,4′-diphenylmethane diisocyanate and polyether polyol, was degraded by glycol and ethanolamine at 170 °C. Optimum conditions for the glycolysis of thermoplastic polyurethane were investigated by adjusting the ratio of polymer to degradation reagent, glycol to ethanolamine as well as the reaction temperature. The degradation reaction was conducted under nitrogen atmosphere and accelerated by catalysts such as lithium acetate, which was evidenced by lowering the degradation temperature as well as the amounts of degradation reagent. The decomposition products were completely separated into two layers. The upper liquid layer was a polyether polyol, which was characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The present glycolysis procedure allows a simple recycling of the hydroxyl terminated polyol in pure form.